+ octet generation for messages only just before the message is sent
+ two additional constructors for query messages + rename "question" to "query" when variable hold a dns-message
This commit is contained in:
mainzelm
parent
4898196703
commit
73629e6baa
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@ -399,43 +399,14 @@
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(map (lambda (elem) (force-ip elem)) names))
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;;; -- message constructors: encode to octet-messages
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;; makes an message header
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(define (make-octet-header id header-flags question-count answer-count
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nameserver-count additional-count)
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(let* ((header-id (number->octet-pair id))
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(header-question-count (number->octet-pair question-count))
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(header-answer-count (number->octet-pair answer-count))
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(header-nameserver-count (number->octet-pair nameserver-count))
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(header-additional-count (number->octet-pair additional-count)))
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(append header-id
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header-flags
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header-question-count
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header-answer-count
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header-nameserver-count
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header-additional-count)))
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(define (make-octet-header-flags qr opcode aa tc rd ra zero response-code)
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(list
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(ascii->char (+ (arithmetic-shift qr 7)
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(arithmetic-shift opcode 3)
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(arithmetic-shift aa 2)
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(arithmetic-shift tc 1)
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rd))
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(ascii->char (+ (arithmetic-shift ra 7)
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(arithmetic-shift zero 4)
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response-code))))
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;; a standard query header, usefull for most queries
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(define (make-std-octet-query-header id question-count)
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(let* ((qr 0) ; querytype: query 0, response 1
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(define (make-std-query-header id question-count)
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(let* ((qr 'query) ; querytype: query 0, response 1
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(opcode 0) ; opcode: query 0, iquery 1 (OBSOLETE), status 2
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(aa 0) ; authorative answer (in answers only)
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(tc 0) ; truncation (size matters only with UDP)
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(rd 1) ; recursion desired: nameserver pursues the query recursivly (optional)
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(ra 0) ; recursion available (in answers only)
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(aa #f) ; authorative answer (in answers only)
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(tc #f) ; truncation (size matters only with UDP)
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(rd #t) ; recursion desired: nameserver pursues the query recursivly (optional)
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(ra #f) ; recursion available (in answers only)
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(zero 0) ; future use
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(response-code 0) ; response code: error conditions (in answers only)
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(question-count question-count)
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@ -443,25 +414,24 @@
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(nameserver-count 0) ; name server resources (in answers only)
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(additional-count 0)) ; additional records (in answers only)
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(make-octet-header id
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(make-octet-header-flags qr opcode aa tc rd ra zero response-code)
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question-count answer-count nameserver-count additional-count)))
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;; makes a question (name, type, class)
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(define (make-octet-question name type class)
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(let* ((qname (name->octets name))
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(qtype (number->octet-pair (message-type-number type)))
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(qclass (number->octet-pair (message-class-number class))))
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(append qname qtype qclass)))
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(make-header
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id
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(make-flags qr opcode aa tc rd ra zero response-code)
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question-count answer-count nameserver-count additional-count)))
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;; makes a query-message (header and question only)
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(define (make-octet-query-message id name type class)
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(append
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(make-std-octet-query-header id 1)
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(make-octet-question name type class)))
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;; TODO does this really work for several questions as well?
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(define (make-query-dns-message header . questions)
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(make-message header questions '() '() '()
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(apply
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append
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(header->octets header)
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(map question->octets questions))))
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(define (make-simple-query-dns-message id name type class)
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(make-query-dns-message (make-std-query-header id 1)
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(make-question name type class)))
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;; makes a resource record for ans, nss, ars (name, type, class, ttl, data)
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(define (make-octet-rr name type class ttl rdata)
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@ -510,6 +480,24 @@
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(nameserver-count header-nameserver-count)
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(additional-count header-additional-count))
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;;; -- message constructors: encode to octet-messages
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;; makes an message header
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(define (header->octets header)
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(let* ((header-id (number->octet-pair (header-id header)))
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(header-question-count (number->octet-pair (header-question-count header)))
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(header-answer-count (number->octet-pair (header-answer-count header)))
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(header-nameserver-count (number->octet-pair
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(header-nameserver-count header)))
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(header-additional-count (number->octet-pair
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(header-additional-count header))))
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(append header-id
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(flags->octets (header-flags header))
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header-question-count
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header-answer-count
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header-nameserver-count
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header-additional-count)))
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;; flags
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(define-record-type flags :flags
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(make-flags query-type opcode authoritative? truncated? recursion-desired?
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@ -543,6 +531,23 @@
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((4) 'dns-not-implemented)
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((5) 'dns-refused))))
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(define (flags->octets flags)
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(define (boolean->0/1 bool)
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(if bool 1 0))
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(list
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(ascii->char (+ (arithmetic-shift
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(if (eq? (flags-query-type flags) 'query) 0 1) 7)
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(arithmetic-shift (flags-opcode flags) 3)
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(arithmetic-shift
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(boolean->0/1 (flags-authoritative? flags)) 2)
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(arithmetic-shift
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(boolean->0/1 (flags-truncated? flags)) 1)
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(boolean->0/1 (flags-recursion-desired? flags))))
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(ascii->char (+ (arithmetic-shift
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(boolean->0/1 (flags-recursion-available? flags)) 7)
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(arithmetic-shift (flags-zero flags) 4)
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(flags-response-code flags)))))
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;; question
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(define-record-type question :question
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@ -552,6 +557,15 @@
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(type question-type)
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(class question-class))
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;; makes a question (name, type, class)
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(define (question->octets q)
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(let* ((qname (name->octets (question-name q)))
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(qtype (number->octet-pair
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(message-type-number (question-type q))))
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(qclass (number->octet-pair
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(message-class-number (question-class q)))))
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(append qname qtype qclass)))
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;;type rr
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(define-record-type rr :rr
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(make-rr name type class ttl data)
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@ -825,19 +839,16 @@
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;; checks if the received reply is valid. returns #t or error-msg.
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(define (reply-acceptable? reply query)
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;; Check correct id
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(if (not (and (char=? (car reply) (car query))
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(char=? (cadr reply) (cadr query))))
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;; TODO replace display
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(display "send-receive-message: bad reply id from server"))
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(if (not (= (header-id (message-header reply))
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(header-id (message-header query))))
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;; TODO replace error
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(error "send-receive-message: bad reply id from server"))
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;; Check for error code:
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(let ((response-code (flags-response-code (parse-flags reply))))
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(let ((response-code (flags-response-code
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(header-flags (message-header reply)))))
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(if (not (eq? response-code 'dns-no-error))
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(dns-error response-code))))
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;; #t if message is truncated (could happen via UDP)
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(define (truncated? reply)
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(flags-truncated? (parse-flags reply)))
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;; connects to nameserver and sends and receives messages. returns the reply.
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;; here: via TCP
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(define (send-receive-message-tcp nameservers query)
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@ -864,9 +875,10 @@
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(sock (cdr (assoc w wport-socket-alist))))
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(if (not (connect-socket-successful? sock))
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(dns-error 'bad-nameserver hit-ns))
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(let ((query-string (list->string query))
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(let ((query-string
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(add-size-tag (list->string (message-source query))))
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(r (socket:inport sock)))
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(display (list->string (add-size-tag query)) w)
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(display (list->string query-string) w)
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(force-output w)
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(let ((a (read-char r))
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(b (read-char r)))
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@ -874,13 +886,13 @@
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(let ((s (read-string len r)))
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(if (not (= len (string-length s)))
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(dns-error 'unexpected-eof-from-server))
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(values (string->list s)
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(values (parse (string->list s))
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hit-ns
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(delete hit-ns nameservers))))))))
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(lambda ()
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(for-each close-socket sockets)))))
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(reply-acceptable? reply query)
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(values (parse reply)
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(values reply
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hit-ns
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other-nss)))
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@ -901,7 +913,7 @@
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(lambda ()
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'nothing-to-be-done-before)
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(lambda ()
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(let ((query-string (list->string query))
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(let ((query-string (list->string (message-source query)))
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(rsv (list->vector rs))
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(rport-nameserver-alist (map cons rs nameservers))
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(rport-socket-alist (map cons rs sockets)))
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@ -913,15 +925,15 @@
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(if (not (connect-socket-successful? (cdr (assoc r rport-socket-alist))))
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(dns-error 'bad-nameserver hit-ns))
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;;; 512 is the maximum udp-message size:
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(values (string->list (read-string/partial 512 r))
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(values (parse (string->list (read-string/partial 512 r)))
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hit-ns
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(delete hit-ns nameservers)))))
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(lambda ()
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(for-each close-socket sockets)))))
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(reply-acceptable? reply query)
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(if (truncated? reply)
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(if (flags-truncated? (header-flags (message-header reply)))
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(send-receive-message-tcp nameservers query)
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(values (parse reply)
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(values reply
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hit-ns
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other-nss))))
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@ -981,47 +993,47 @@
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(define (update-cache! key entry)
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(table-set! cache key entry))
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(define (dns-query-no-cache question protocol nameservers tried)
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(define (dns-query-no-cache query protocol nameservers tried)
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;; returns new retrieved data
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(receive (dns-msg hit-ns nss-with-no-reply)
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(send-receive-message nameservers question protocol)
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(send-receive-message nameservers query protocol)
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(values
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(make-dns-message (parse question) dns-msg #f protocol (reverse tried))
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(make-dns-message query dns-msg #f protocol (reverse tried))
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hit-ns
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nss-with-no-reply)))
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(define (dns-query-with-cache question protocol nameservers tried)
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(let ((qds (message-questions (parse question))))
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(define (dns-query-with-cache query protocol nameservers tried)
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(let ((qds (message-questions query)))
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(let lp ((ns nameservers))
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(if (null? ns)
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(receive (reply-msg hit-ns nss-with-no-reply)
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(send-receive-message nameservers question protocol)
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(send-receive-message nameservers query protocol)
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(update-cache! (make-key qds hit-ns)
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(make-cache reply-msg (find-shortest-ttl reply-msg) (time)))
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;; returns new retrieved data and updates cache
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(values (make-dns-message (parse question) reply-msg #f protocol (reverse tried))
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(values (make-dns-message query reply-msg #f protocol (reverse tried))
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hit-ns
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nss-with-no-reply))
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(cond ((lookup-cache qds (car ns))
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=> (lambda (found-data)
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;; returns cached data
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(values (make-dns-message (parse question) (cache-answer found-data) #t protocol '())
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(values (make-dns-message query (cache-answer found-data) #t protocol '())
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#f
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nameservers)))
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(else (lp (cdr ns))))))))
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(define (send-receive-message nameservers question protocol)
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(define (send-receive-message nameservers query protocol)
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((cond
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((eq? protocol 'tcp) send-receive-message-tcp)
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((eq? protocol 'udp) send-receive-message-udp))
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nameservers question))
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nameservers query))
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;; makes a dns-query. optional cache-check.
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;; returns a dns-message with cache-flag and either cache-data or new received data.
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(define (dns-query/cache question use-cache? protocol nameservers tried)
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(define (dns-query/cache query use-cache? protocol nameservers tried)
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(if use-cache?
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(dns-query-with-cache question protocol nameservers tried)
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(dns-query-no-cache question protocol nameservers tried)))
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(dns-query-with-cache query protocol nameservers tried)
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(dns-query-no-cache query protocol nameservers tried)))
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;; dns and recursion
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;; recursion means, if the demanded information is not available from the
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@ -1030,12 +1042,12 @@
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;; this feature is technically optional (RFC 1035).
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;; dns-get-information implements the resovler-side recursion.
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;; it returns a dns-message
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(define (dns-get-information question use-cache? protocol nameservers check-answer)
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(define (dns-get-information query use-cache? protocol nameservers check-answer)
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(let lp ((tried '()) (nss nameservers))
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(if (null? nss)
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(dns-error 'bad-address)
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(receive (dns-msg hit-ns nss-with-no-reply)
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(dns-query/cache question use-cache? protocol nss tried)
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(dns-query/cache query use-cache? protocol nss tried)
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(if (check-answer dns-msg)
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dns-msg
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(let ((auth? (flags-authoritative? (header-flags
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@ -1247,14 +1259,15 @@
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(let* ((maybe-ip-string (if (address32? name)
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(ip-string->in-addr-arpa (address32->ip-string name))
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(ip-string->in-addr-arpa name)))
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(question (if maybe-ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
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(make-octet-query-message (random 256) maybe-ip-string type (message-class in))
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(make-octet-query-message (random 256) name type (message-class in))))
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(query (if maybe-ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
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(make-simple-query-dns-message
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(random 256) maybe-ip-string type (message-class in))
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(make-simple-query-dns-message (random 256) name type (message-class in))))
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(use-cache? #t)
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(protocol 'udp)
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(nameservers (check-args nameservers))
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(check-answer (lambda (dns-msg) #t))
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(dns-msg (dns-get-information question use-cache? protocol nameservers check-answer))
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(dns-msg (dns-get-information query use-cache? protocol nameservers check-answer))
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(answers (message-answers (dns-message-reply dns-msg))))
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dns-msg))
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@ -1265,9 +1278,9 @@
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(let* ((maybe-ip-string (if (address32? name)
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(ip-string->in-addr-arpa (address32->ip-string name))
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(ip-string->in-addr-arpa name)))
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(question (if maybe-ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
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(dns-error 'not-a-hostname)
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(make-octet-query-message (random 256) name (message-type a) (message-class in))))
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(query (if maybe-ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
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(dns-error 'not-a-hostname)
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(make-simple-query-dns-message (random 256) name (message-type a) (message-class in))))
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(use-cache? #t)
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(protocol 'udp)
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(nameservers (check-args nameservers))
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@ -1275,7 +1288,7 @@
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(let* ((reply (dns-message-reply dns-msg))
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(answers (message-answers reply)))
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(not (null? (filter-type answers (message-type a)))))))
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(dns-msg (dns-get-information question use-cache? protocol nameservers check-answer))
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(dns-msg (dns-get-information query use-cache? protocol nameservers check-answer))
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(answers (filter-type (message-answers (dns-message-reply dns-msg)) (message-type a))))
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(rr-data-a-ip (rr-data (car answers)))))
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@ -1285,9 +1298,9 @@
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(let* ((maybe-ip-string (if (address32? ip)
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(ip-string->in-addr-arpa (address32->ip-string ip))
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(ip-string->in-addr-arpa ip)))
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(question (if maybe-ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
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(make-octet-query-message (random 256) maybe-ip-string (message-type ptr) (message-class in))
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(dns-error 'not-a-ip)))
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(query (if maybe-ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
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(make-simple-query-dns-message (random 256) maybe-ip-string (message-type ptr) (message-class in))
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(dns-error 'not-a-ip)))
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(use-cache? #t)
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(protocol 'udp)
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(nameservers (check-args nameservers))
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@ -1295,7 +1308,7 @@
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(let* ((reply (dns-message-reply dns-msg))
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(answers (message-answers reply)))
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(not (null? (filter-type answers (message-type ptr)))))))
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(dns-msg (dns-get-information question use-cache? protocol nameservers check-answer))
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(dns-msg (dns-get-information query use-cache? protocol nameservers check-answer))
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(answers (filter-type (message-answers (dns-message-reply dns-msg)) (message-type ptr))))
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(rr-data-ptr-name (rr-data (car answers)))))
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@ -1308,9 +1321,10 @@
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(let* ((maybe-ip-string (if (address32? name)
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(ip-string->in-addr-arpa (address32->ip-string name))
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(ip-string->in-addr-arpa name)))
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(question (if maybe-ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
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(dns-error 'not-a-hostname)
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(make-octet-query-message (random 256) name (message-type ns) (message-class in))))
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(query (if maybe-ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
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(dns-error 'not-a-hostname)
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(make-simple-query-dns-message
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(random 256) name (message-type ns) (message-class in))))
|
||||
(use-cache? #t)
|
||||
(protocol 'udp)
|
||||
(nameservers (check-args nameservers))
|
||||
|
|
@ -1320,7 +1334,7 @@
|
|||
(nameservers (message-nameservers reply)))
|
||||
(or (not (null? (filter-type nameservers (message-type soa))))
|
||||
(not (null? (filter-type answers (message-type ns))))))))
|
||||
(dns-msg (dns-get-information question use-cache? protocol nameservers check-answer))
|
||||
(dns-msg (dns-get-information query use-cache? protocol nameservers check-answer))
|
||||
(reply (dns-message-reply dns-msg))
|
||||
(soa (filter-type (message-nameservers reply) (message-type soa)))
|
||||
(nss (filter-type (message-answers reply) (message-type ns)))
|
||||
|
|
@ -1338,9 +1352,10 @@
|
|||
(let* ((ip-string (if (address32? name)
|
||||
(ip-string->in-addr-arpa (address32->ip-string name))
|
||||
(ip-string->in-addr-arpa name)))
|
||||
(question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
|
||||
(dns-error 'not-a-hostname)
|
||||
(make-octet-query-message (random 256) name (message-type mx) (message-class in))))
|
||||
(query (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
|
||||
(dns-error 'not-a-hostname)
|
||||
(make-simple-query-dns-message
|
||||
(random 256) name (message-type mx) (message-class in))))
|
||||
(use-cache? #t)
|
||||
(protocol 'tcp)
|
||||
(nameservers (check-args nameservers))
|
||||
|
|
@ -1351,7 +1366,7 @@
|
|||
(or (not (null? (filter-type answers (message-type mx))))
|
||||
(not (null? (filter-type answers (message-type cname))))
|
||||
(not (null? (filter-type answers (message-type a))))))))
|
||||
(dns-msg (dns-get-information question use-cache? protocol nameservers check-answer))
|
||||
(dns-msg (dns-get-information query use-cache? protocol nameservers check-answer))
|
||||
(reply (dns-message-reply dns-msg))
|
||||
(mx (filter-type (message-answers reply) (message-type mx)))
|
||||
(soa (filter-type (message-nameservers reply)(message-type soa)))
|
||||
|
|
|
|||
Loading…
Reference in New Issue